I've only done it a few times so far so it's pretty easy to look at the stats.
I've shot 79 with as little as 4 GIRs, but typically 6 or more gives a chance as long as putting is OK and there are no throwaways. Personal best is 74 with 10 greens, 2 birdies, 5 u&d, 1 double.
On the other hand I've shot 80 twice with 10 GIR's, 36 puts, 1 u&d (same course both time with the same stats!). Once I shot 80 with 8 greens, 32 puts (two 3-puts), 3 birdies and then 10 on a par5 (2 OB's).
Brian seems to know what he's talking about (as usual).